An estimated 1.2 million new HIV infections occur among 15 to 24 year olds annually in the world. In the US, the HIV incidence rate in youth is among the highest with 34% of all new infections occurring among 13-29 year olds in 2006. Data from the Colorado Department of Health and Environment indicate an annual increase in the number of young people acquiring HIV infection as well as a steady increase in the number of youth with other sexually transmitted infections, indicating that a large number of adolescents and young adults are participating in behavior that puts them at risk of HIV infection. The goal of this proposal is to establish a new Adolescent Trials Network Unit in metropolitan Denver. The unit will participate fully with the ATN operations to conduct studies focused on primary, secondary and tertiary prevention of HIV infection in adolescents and young adults (age 12-24yr). The work will be take place primarily at The Children's Hospital which is affiliated with University of Colorado Denver as well as in the communities where at-risk youth receive services. The applicant has over 18 years of experience participating in multi-centered clinical trials for HIV infected and at-risk individuals. Our research unit has established a record of achievement in regard to data quality and contributions to the scientific agenda of the clinical trials networks in which we have participated. CHIP Youth Project is a robust program for the care of HIV-infected youth and is the lead agency in Denver's collaborative community consortium, the Youth HIV Advocacy Coalition (YHAC), dedicated to the prevention of HIV. These attributes position our site to be a highly productive ATN unit. The specific aims of the project will be to 1) Integrate Adolescent Trials Network protocols into the research and care operation of CHIP/CYP; 2) Expand and enhance existing community collaborations resulting in community mobilization to reduce HIV transmission; 3) Use innovation strategies to recruit and retain more than 75 HIV infected and 125 HIV at-risk adolescents and young adults; 4) Maintain outstanding performance as an ATN unit; 5) Contribute to the ATN scientific agenda; 6) Develop methods to assure consumer input to scientific agenda and research operations. RELEVANCE: The research conducted in this proposal, in collaboration with other research units and the ATN leadership, will lead to improved interventions to prevent HIV transmission among youth (age 12-24 years) and to better care to prevent disease progression and improve quality of life for youth living with HIV.